1. Field of the Invention
The present invention relates to an image signal processing system and a camera having the image signal processing system.
2. Description of the Related Art
Conventionally, a so-called electronic still camera or a digital camera (hereinafter, referred to as an electronic camera or simply referred to as a camera) is generally and widely spread. In the electronic camera, a subject image which is optically formed by using a photographing optical system having a photographing lens and the like is photoelectrically converted by image pick-up means including an image pick-up device and the like such as a charge coupled device (hereinafter, briefly referred to as a CCD). The photoelectrically converted electrical signal (image signal indicating an image) is subjected to compression processing such as a predetermined-form image data (e.g., JPEG (Joint Photographic Experts Group)) method and is electronically recorded.
In the conventional electronic camera using the CCD as the image pick-up means, normally, an output signal, namely, an image signal generated and outputted through photoelectric conversion processing using the image pick-up device (CCD) mixedly includes random noises such as shot noise.
Then, in the above-mentioned conventional electronic camera, an operation for displaying a preferred image to display means generally requires various signal processing for suppressing or removing noise components and the like from an output signal (image signal) from the image pick-up device (CCD). Usually, an operation for accurately displaying the subject image to be displayed based on the image signal further requires various signal processing of the image signal, such as various correction processing.
Hence, the general and conventional electronic camera comprises a system for generating an image signal or image data which is most proper to a display operation of the image or a recording operation of the electrical signal indicating the image based on the output signal from the image pick-up device (CCD), namely, an image signal processing system.
For example, Japanese Unexamined Patent Application Publication No. 9-130816, Japanese Unexamined Patent Application Publication No. 11-112837, etc. propose the above-mentioned conventional image signal processing systems.
In the image signal processing system disclosed in Japanese Unexamined Patent Application Publication No. 9-130816, the image signal is subjected to coring processing and gamma correction processing. Further, the image signal is subjected to edge emphasis processing (contour correction processing), luminance signal generation processing, and chroma signal generation processing based on the output signal generated by the gamma correction processing.